////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
///  File:        AES_Key.h
///  Description: The class that creates all the keys needed by each
///               round of AES algorithm.
///  Author:      Chiuta Adrian Marius
///  Created:     23-10-2009
///
///  Licensed under the Apache License, Version 2.0 (the "License");
///  you may not use this file except in compliance with the License.
///  You may obtain a copy of the License at
///  http://www.apache.org/licenses/LICENSE-2.0
///  Unless required by applicable law or agreed to in writing, software
///  distributed under the License is distributed on an "AS IS" BASIS,
///  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
///  See the License for the specific language governing permissions and
///  limitations under the License.
///
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#ifndef __INCLUDED_AES_KEY_H__
#define __INCLUDED_AES_KEY_H__

/// The class that creates all the keys needed by each round of AES algorithm
class AES_Key
{
public:
    /// The possible key size ( in bits ) for AES
    enum AES_KeySize
    {
        AES_KeyInvalid  = 0,
        AES_Key128      = 128,
        AES_Key192      = 192,
        AES_Key256      = 256
    };

    ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    ///
    /// Creates a key to be used with AES algorithm.
    ///
    /// @param pData
    ///                 The pointer to the data needed to create the key.
    /// @param keySize
    ///                 The size in bits of the data found at pData address.
    ///
    ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    AES_Key(const UINT8 *pData, AES_KeySize keySize)
    {
        static const UINT8 nullKey[16] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};

        m_data = NULL;
        m_keySize = AES_KeyInvalid;

        if( pData == NULL || (keySize != AES_Key::AES_Key128 &&
            keySize != AES_Key::AES_Key192 && keySize != AES_Key::AES_Key256) )
        {
            SetKeyData(nullKey, AES_Key128);
        }
        else
            SetKeyData(pData, keySize);
    }

    ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    ///
    /// Creates a key to be used with AES algorithm.
    ///
    /// @param pData
    ///                 The pointer to the data needed to create the key.
    /// @param keySize
    ///                 The size in bits of the data found at pData address.
    /// @return
    ///                 True if everything is OK.
    ///
    ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    bool SetKeyData(const UINT8 *pData, AES_KeySize keySize)
    {
        static const UINT8 sbox[256] =
        {
            //0     1    2      3     4    5     6     7      8    9     A      B    C     D     E     F
            0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76, //0
            0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0, //1
            0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15, //2
            0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75, //3
            0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84, //4
            0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf, //5
            0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8, //6
            0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2, //7
            0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73, //8
            0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb, //9
            0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79, //A
            0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08, //B
            0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a, //C
            0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e, //D
            0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf, //E
            0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16  //F
        };

        // The round constant word array, Rcon[i], contains the values given by 
        // x to th e power (i-1) being powers of x (x is denoted as {02}) in the field GF(28)
        // Note that i starts at 1, not 0).
        static const UINT8 Rcon[255] =
        {
            0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a,
            0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39,
            0x72, 0xe4, 0xd3, 0xbd, 0x61, 0xc2, 0x9f, 0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a,
            0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8,
            0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef,
            0xc5, 0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd, 0x61, 0xc2, 0x9f, 0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc,
            0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b,
            0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3,
            0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd, 0x61, 0xc2, 0x9f, 0x25, 0x4a, 0x94,
            0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20,
            0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35,
            0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd, 0x61, 0xc2, 0x9f,
            0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04,
            0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63,
            0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd,
            0x61, 0xc2, 0x9f, 0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb
        };

        if( pData == NULL || (keySize != AES_Key::AES_Key128 &&
            keySize != AES_Key::AES_Key192 && keySize != AES_Key::AES_Key256) )
            return false;

        UINT32  Nk = keySize >> 5, // The number of 32 bit words in the key
                Nb = 4, // The number of 32 bit words in one input block ( is constant for AES )
                Nr = Nk + 6, // The number of rounds that will be used by the AES algorithm
                i, j;

        m_keySize = keySize;
        delete [] m_data;
        m_data = new UINT8[GetKeySizeBytes()];
        if( m_data == NULL )
            return false;

        // The first round key is the key itself
        for( i = 0; i < 4 * Nk; i++ )
            m_data[i] = pData[i];

        UINT8 temp[4], k;
        i = Nk;

        // All other round keys are found from the previous round keys.
        while( i < (Nb * (Nr+1)) )
        {
            for( j = 0; j < 4; j++ )
                temp[j] = m_data[(i-1) * 4 + j];

            if( i % Nk == 0 )
            {
                // This function rotates the 4 bytes in a word to the left once.
                // [a0,a1,a2,a3] becomes [a1,a2,a3,a0]

                // Function RotWord()
                {
                    k = temp[0];
                    temp[0] = temp[1];
                    temp[1] = temp[2];
                    temp[2] = temp[3];
                    temp[3] = k;
                }

                // SubWord() is a function that takes a four-byte input word and 
                // applies the S-box to each of the four bytes to produce an output word.

                // Function Subword()
                {
                    temp[0] = sbox[temp[0]];
                    temp[1] = sbox[temp[1]];
                    temp[2] = sbox[temp[2]];
                    temp[3] = sbox[temp[3]];
                }

                temp[0] = temp[0] ^ Rcon[i/Nk];
            }
            else if (Nk > 6 && i % Nk == 4)
            {
                // Function Subword()
                {
                    temp[0] = sbox[temp[0]];
                    temp[1] = sbox[temp[1]];
                    temp[2] = sbox[temp[2]];
                    temp[3] = sbox[temp[3]];
                }
            }
            m_data[i*4+0] = m_data[(i-Nk)*4+0] ^ temp[0];
            m_data[i*4+1] = m_data[(i-Nk)*4+1] ^ temp[1];
            m_data[i*4+2] = m_data[(i-Nk)*4+2] ^ temp[2];
            m_data[i*4+3] = m_data[(i-Nk)*4+3] ^ temp[3];
            i++;
        }

        return true;
    }

    ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    ///
    /// @return         The pointer to the expanded data of the key (all the key rounds needed by the AES).
    ///
    ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    const UINT8* GetKeyData() const { return m_data; }

    ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    ///
    /// @return         The size of the key in bits.
    ///
    ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    AES_KeySize GetKeySize() const { return m_keySize; }

    ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    ///
    /// @return         The size of the key in bytes.
    ///
    ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    UINT32 GetKeySizeBytes() const { return 4 * 4 * ((m_keySize >> 5) + 7); }

    ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    ///
    /// Frees all the resources associated with the key.
    ///
    ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    ~AES_Key() { delete[] m_data; }

private:
    /// The pointer to the key data (all the key rounds needed by the AES)
    UINT8 *m_data;

    /// The size of the AES key
    AES_KeySize m_keySize;
};

#endif // __INCLUDED_AES_KEY_H__
